Hypertext is a term used to describe a particular organization of information within a computer system and its presentation to a user. Hypertext exploits the computer's ability to link together information from a wide variety of sources to provide the user with the ability to explore a particular topic. The traditional style of presentation used in books employs an organization of the information that is imposed upon it by limitations of the medium, namely fixed sized, sequential paper pages. Hypertext systems, however, use a large number of units of text or other types of data such as image information, graphical information, video information or sound information, which can vary in size. A collection of such units of information is termed a hypertext document. Sometimes hypertext documents employing information other than text are termed hypermedia documents.
Each of the different units in a hypertext document is generally self-contained but contains references to other units. The references are made explicit in the form of “links”. Each link is a relation between locations in two units of information. When a portion of a unit of information is displayed, links to locations in the displayed portion are indicated on the display to the user. A link can then act as a user-activated control. A user can act on a displayed link, either by clicking on it with a mouse to cause the particular unit that is the link target to be displayed. Typically, hypertext systems are window-based and the newly displayed unit appears in a new window. The new unit may, of course, contain further links that can be similarly activated to display other units of information. By following links the user may “navigate” around the document. The user has a great deal of control over the order in which information is presented and can play a very active role in selecting what is of interest and how far to pursue a given topic.
In one prior art method of hypertext display the contents of a link are displayed not in a new page but in a region in the middle of the present page, right below the link. If the contents of the link has in turn its own links, their contents can be displayed within a smaller sub-region, so that the nested displays produce a “boxes within boxes” appearance, with each box visually adjacent to the link which invoked it.
A tremendous amount of cost and effort is spent discovering and analyzing errors in computer programs. Computer programs are typically written as collections of functions which call other functions, and programmers seeking to understand or debug those programs have a need to visualize the nested structure of the program, while keeping the display of the called function visually adjacent to its point of its invocation in the calling function. Standard methods of hypertext display do not provide such a visualization.